export_comments.bml

Metadata should be cached but can be modified. Should I perform full update of metadata periodically? Does that mean that I shouldn't do this too often?

The pseudocode for get=comment_body says: "if nothing was returned". What does "nothing" actually mean? XML with only maxid?

"startid+1000 < maxid from metadata, call download_comments again": Should I run download_comments with the same startid (i.e. repeat the same request)? Where 1000 comes from? Or does this mean that I have to skip 1000 comments and there is no way to download them?